Add binary search to Nim track

config.json

@@ -248,6 +248,20 @@
           "strings"
         ]
       },
+      {
+        "slug": "binary-search",
+        "name": "Binary Search",
+        "uuid": "1b8f461e-8f44-4de2-be57-f3c2934cecf7",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2,
+        "topics": [
+          "arrays",
+          "control_flow_if_else_statements",
+          "control_flow_loops",
+          "searching"
+        ]
+      },
       {
         "slug": "word-count",
         "name": "Word Count",

exercises/practice/binary-search/.docs/instructions.md

@@ -0,0 +1,24 @@
+# Instructions
+
+Implement a binary search algorithm.
+
+Searching a sorted collection is a common task.
+A dictionary is a sorted list of word definitions.
+Given a word, one can find its definition.
+A telephone book is a sorted list of people's names, addresses, and telephone numbers.
+Knowing someone's name allows one to quickly find their telephone number and address.
+
+If the list to be searched contains more than a few items (a dozen, say) a binary search will require far fewer comparisons than a linear search, but it imposes the requirement that the list be sorted.
+
+In computer science, a binary search or half-interval search algorithm finds the position of a specified input value (the search "key") within an array sorted by key value.
+
+In each step, the algorithm compares the search key value with the key value of the middle element of the array.
+
+If the keys match, then a matching element has been found and its index, or position, is returned.
+
+Otherwise, if the search key is less than the middle element's key, then the algorithm repeats its action on the sub-array to the left of the middle element or, if the search key is greater, on the sub-array to the right.
+
+If the remaining array to be searched is empty, then the key cannot be found in the array and a special "not found" indication is returned.
+
+A binary search halves the number of items to check with each iteration, so locating an item (or determining its absence) takes logarithmic time.
+A binary search is a dichotomic divide and conquer search algorithm.

exercises/practice/binary-search/.meta/.config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "razvbir-646"
+  ],
+  "files": {
+    "solution": [
+      "binary_search.nim"
+    ],
+    "test": [
+      "test_binary_search.nim"
+    ],
+    "example": [
+      ".meta/example.nim"
+    ]
+  },
+  "blurb": "Implement a binary search algorithm.",
+  "source": "Wikipedia",
+  "source_url": "http://en.wikipedia.org/wiki/Binary_search_algorithm"
+}

exercises/practice/binary-search/.meta/example.nim

@@ -0,0 +1,5 @@
+import std/algorithm
+
+func binarySearch*(haystack: openArray[int], needle: int): int =
+  binarySearch(haystack, needle, system.cmp[int])
+

exercises/practice/binary-search/.meta/tests.toml

@@ -0,0 +1,44 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[b55c24a9-a98d-4379-a08c-2adcf8ebeee8]
+description = "finds a value in an array with one element"
+
+[73469346-b0a0-4011-89bf-989e443d503d]
+description = "finds a value in the middle of an array"
+
+[327bc482-ab85-424e-a724-fb4658e66ddb]
+description = "finds a value at the beginning of an array"
+
+[f9f94b16-fe5e-472c-85ea-c513804c7d59]
+description = "finds a value at the end of an array"
+
+[f0068905-26e3-4342-856d-ad153cadb338]
+description = "finds a value in an array of odd length"
+
+[fc316b12-c8b3-4f5e-9e89-532b3389de8c]
+description = "finds a value in an array of even length"
+
+[da7db20a-354f-49f7-a6a1-650a54998aa6]
+description = "identifies that a value is not included in the array"
+
+[95d869ff-3daf-4c79-b622-6e805c675f97]
+description = "a value smaller than the array's smallest value is not found"
+
+[8b24ef45-6e51-4a94-9eac-c2bf38fdb0ba]
+description = "a value larger than the array's largest value is not found"
+
+[f439a0fa-cf42-4262-8ad1-64bf41ce566a]
+description = "nothing is found in an empty array"
+
+[2c353967-b56d-40b8-acff-ce43115eed64]
+description = "nothing is found when the left and right bounds cross"
+include = false

exercises/practice/binary-search/binary_search.nim

@@ -0,0 +1,4 @@
+
+func binarySearch*(haystack: openArray[int], needle: int): int =
+  discard
+

exercises/practice/binary-search/test_binary_search.nim

@@ -0,0 +1,36 @@
+import unittest
+import binary_search
+
+suite "Binary Search":
+  test "finds a value in an array with one element":
+    check binarySearch([6], 6) == 0
+
+  test "finds a value in the middle of the array":
+    check binarySearch([1, 3, 4, 6, 8, 9, 11], 6) == 3
+
+  test "finds a value at the beginning of the array":
+    check binarySearch([1, 3, 4, 6, 8, 9, 11], 1) == 0
+
+  test "finds a value at the end of the array":
+    check binarySearch([1, 3, 4, 6, 8, 9, 11], 11) == 6
+
+  test "finds a value in an array of odd length":
+    check binarySearch([1, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 634], 144) == 9
+
+  test "finds a value in an array of even length":
+    check binarySearch([1, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377], 21) == 5
+
+  test "identifies that a value is not included in the array":
+    check binarySearch([1, 3, 4, 6, 8, 9, 11], 7) == -1
+
+  test "a value smaller than the array's smallest value is not found":
+    check binarySearch([1, 3, 4, 6, 8, 9, 11], 0) == -1
+
+  test "a value larger than the array's largest value is not found":
+    check binarySearch([1, 3, 4, 6, 8, 9, 11], 13) == -1
+
+  test "nothing is found in an empty array":
+    check binarySearch([], 1) == -1
+
+  test "nothing is found when the left and right bounds cross":
+    check binarySearch([1, 2], 0) == -1